import html2Canvas from 'html2canvas';
import jsPDF from 'jspdf';

const htmlToPdf = {
    getPdf: async function (title) {
        // Capture the sign element
        html2Canvas(document.querySelector('#pdfDom'), {
            allowTaint: false,
            taintTest: false,
            logging: false,
            useCORS: true,
            dpi: window.devicePixelRatio * 4, // 将分辨率提高到特定的DPI 提高四倍
            scale: 4, // 按比例增加分辨率
        }).then((canvas) => {
            var pdf = new jsPDF('p', 'mm', 'a4'); // A4纸，纵向
            var ctx = canvas.getContext('2d'),
                a4w = 190,
                a4h = 272, // A4大小，210mm x 297mm，四边各保留10mm的边距，显示区域190x277
                imgHeight = Math.floor((a4h - 10) * canvas.width / a4w), // 按A4显示比例换算一页图像的像素高度
                renderedHeight = 0;

            while (renderedHeight < canvas.height) {
                var page = document.createElement('canvas');
                page.width = canvas.width;
                page.height = Math.min(imgHeight, canvas.height - renderedHeight); // 可能内容不足一页

                // 用getImageData剪裁指定区域，并画到前面创建的canvas对象中
                page
                    .getContext('2d')
                    .putImageData(
                        ctx.getImageData(
                            0,
                            renderedHeight,
                            canvas.width,
                            Math.min(imgHeight, canvas.height - renderedHeight),
                        ),
                        0,
                        0,
                    );

                renderedHeight += imgHeight;
                if (renderedHeight < canvas.height) {
                    pdf.addPage(); // 如果后面还有内容，添加一个空页
                }
            }

            // 保存文件
            pdf.save(title + '.pdf');

        }).finally(() => {
        });
    },
};

export default htmlToPdf;
